1. FIELD OF THE INVENTION
The present invention relates to a counting system having one or more counters which is used for a maintenance and a charge calculation of a copying machine.
2. DESCRIPTION OF THE PRIOR ART
There has been provided a counter in a copying machine for counting times of copying operation so as to perform the maintenance of the copying machine such as exchange of a developing unit and to count the charge rent of copying machine on the basis of the count value of the counter.
In the counter system mentioned above, after a toner image is transferred and fixed onto a copying sheet through a copying operation, the counter is increased by 1 at the time of discharging the copying sheet on which the image is fixed. In the conventional counter system it has been known to provide either a total counter which counts the total value of the times of the copying operation and a size counter which counts the number of the copy in every size of the copying sheet.
Besides, there has been previously proposed a copying machine which is capable of color copy in more than two colors in one exposure (referred to as simultaneous color copying machine hereinafter) by Canon Inc. in the Japanese Patent Laid Open (unexamined) No.61-203474, wherein there are provided a plurality of developing units in the copying machine, which are switched during one exposure operation so that a picture with partially different color can be printed on a copying sheet. According to the simultaneous color copying machine mentioned above, it is possible to copy the right and left portions of an original document with different colors and or to copy a specific portion of the original document in a different color so as to emphasize the specific portion. Since such different color copy can be made by executing one time copying operation, there are advantages that the work of setting an original document and of operating the copying machine can be saved and that the time necessary for copying operation can be greatly reduced.
In the simultaneous color a copying machine there is, however, a problem that what and how should be counted for performing the maintenance and charge calculation thereof properly.